The present invention relates to microwave and millimeter-wave solid state devices. In particular, the present invention relates to monolithic microwave integrated circuits. In particular, the present invention relates to a voltage-controlled oscillator (VCO) for operation at millimeter-wave frequencies (above 30 GHz).
Numerous methods have been used in the microwave art to configure voltage-controlled oscillators (VCO). VCOs are essential to many microwave applications, such as chirped radar and electronic counter measures, in addition to the general utility of VCOs as circuit elements. However, an important limitation of many prior-art microwave VCOs is frequency range and frequency agility. That is, conventional microwave means such as YIG-tuned oscillators, have important frequency limitations.
Thus it is an object of the present invention to provide a solid-state voltage-controlled oscillator which can operate at 94 GHz.
A further difficulty with the prior art voltage-controlled oscillator circuits is their parasitic reactance. That is, where an active element must be connected to a resonating circuit containing a variable-reactance element, the connections themselves become sources of trouble at millimeter-wave frequencies. That is, it is very difficult to design any connection scheme which will not introduce major and uncertain amounts of reactance, and which will not provide substantial resistive and radiation losses.
Thus it is an object of the present invention to provide a voltage-controlled oscillator wherein the active element is completely integrated with a variable-reactance element.
It is a further object of the present invention to provide a voltage-controlled oscillator wherein the active element is completely integrated with the variable-reactance element, and which is capable of operation at frequencies well in excess of 30 GHz.
A further important desideratum in microwave VCOs is frequency agility. That is, the techniques which are required for high-frequency voltage-controlled oscillation are not always compatible with extreme frequency agility. However, frequency agility is itself necessary for many electronic counter measure applications, and is highly desirable for many chirped radar applications.
Thus it is an object of the present invention to provide a voltage-controlled oscillator which can oscillate and provide frequency agility in excess of 1 GHz per micro second at frequencies in excess of 30 GHz.
An integrated low-loss millimeter-wave phase shifter is also useful for many applications, particularly phased array radar.
Thus it is an object of the present invention to provide an integrated low-loss millimeter-wave phase shifter.